Nuclear Quantum Effects on the Organic Bifurcation Reaction in Microsolvated Water Clusters: Ring-Polymer Molecular...

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Organic Reaction Mechanisms

Background:

• Solvent environments profoundly influence organic reaction mechanisms compared to gas-phase or nonpolar conditions.
• Explicit solvation models, treating individual solvent molecules, are increasingly used to simulate organic reactions, capturing solvent dynamics.
• Nuclear quantum effects (NQEs) are vital for accurate simulations of aqueous systems.

Purpose of the Study:

• To investigate the bifurcation reaction between 2-aminoacrolein and 1,3-butadiene in microsolvated water clusters.
• To compare simulation results using ring-polymer molecular dynamics (RPMD) with classical molecular dynamics (MD).
• To elucidate the impact of NQEs on aqueous reaction branching and proton-transfer kinetics.

Main Methods:

• Simulations of microsolvated (H2O)n clusters (n=5, 15, 45) using ring-polymer molecular dynamics (RPMD).
• Comparison of RPMD results with prior classical molecular dynamics (classical MD) simulations.
• Analysis of branching fractions and proton-transfer events.

Main Results:

• RPMD simulations showed an increased tendency towards the minor (4+2) product pathway compared to classical MD.
• Zero-point energy contributions in RPMD simulations influenced the distribution across vibrational modes.
• RPMD revealed significantly accelerated proton-transfer events, highlighting the role of NQEs.

Conclusions:

• Accurate prediction of aqueous reaction branching behavior necessitates explicit solvation models.
• Rigorous inclusion of nuclear quantum effects (NQEs), including zero-point energy and proton delocalization, is essential for reliable simulations.
• NQEs play a substantial role in aqueous reaction dynamics even at room temperature (300 K).